1. HISTOLOGY OF LARGE INTESTINE
By dr. sobia ibrahim

2. Large intestine Has caecum, colon, rectum and anal canal.
Main functions
Absorption of water
Formation of faecal mass
Production of mucus

3. Its wall follows the same four layered pattern
From inner to outer
Mucosa
Sub mucosa
Muscularis externa
Serosa/adventitia
But
NO villi
No plica circularis

5. Appendices Epiplocae
Tenia coli

6. COLON NO villi / plica circularis Mucosa Submucosa Muscularis externa
Epithelium –coloncytes
Intestinal gland- 0.5mm deep, lined by columnar cells, goblet cells, enteroendocrine & stem cells
Lamina propria- rich in lymphatic tissue, BV, lymphocytes, plasma cells, collagen
Muscularis mucosae- prominent
Submucosa
Muscularis externa
Inner circular
Outer longitudinal – taeniae coli
Serosa / Adventitia

7. colon

8. colon

13. RECTUM Goblet cells abundant Glands deeper -0.75mm
Complete muscle coat
Rest same

15. COMPARISON

16. Medical application Adenocarcinoma of colon Very common in old age
Most common tumor of old age in developed countries
Causes
Low fiber intake
Ulcerative colitis/ other diseases of gut
Family history

17. APPENDIX Irregular lumen Few short intestinal glands Epithelium
Columnar cells
Goblet cells- few
Paneth cells- few
Enteroendocrine cells
M cells
Lamina propria
Diffuse lymphocytic infiltration
Lymphatic nodules
Muscularis mucosae- disrupted
Submucosa- lymphatic tissue etc.
Muscularis externa- two layers
Serosa

18. APPENDIX

19. MEDICAL APPLICATION ACUTE APPDICITIS
Infection & inflammation of appedix
Lymphoid follicle inlarges
Wall rupture

22. ANAL CANAL(upper 1/3) Epithelium: Lamina propria: Muscularis mucosa:
Simple columnar with goblet cells
Lamina propria:
Intestinal glands -short
Muscularis mucosa:
Inner circular
Outer longitudnal
Submusoa:
Loose CT
Branched tubular glands lined with mucous cells
Numerous thin walled veins- Internal hemorrhoidal veins (Piles)

23. ANAL CANAL (middle 1/3) Epithelium: Lamina propria:
Stratified squamous non-keratinized
Lamina propria:
Crypts absent
Muscularis mucosae:
Broken –gradually indistinct
Submucosa

24. ANAL CANAL (lower 2 cm) Epithelium: Lamina propria & Submucosa:
Stratified squamous keratinized
Sweat glands
Sebaceous glands
Lamina propria & Submucosa:
No distinction
Muscularis mucosa:
Absent

25. MUSCULARIS EXTERNA ADVENTITIA Inner circular – internal anal sphincter
Outer longitudinal
Outermost – skeletal muscle – external anal sphincter
ADVENTITIA

29. MEDICAL APPLICATION
Anal fissures
Anal abscesses
Hemorrhoids